The present invention pertains in general to an improved firearm barrel, shroud construction and, more particularly, to a barrel-shroud nut of improved construction for maintaining the concentricity of the barrel relative to the shroud.
It is common in prior art hand guns to provide a relatively tight and intimate fit between the barrel outer diameter and the shroud inner diameter. For example, one patent showing a barrel and shroud arrangement is the Lewis U.S. Pat. No. 3,303,594 which employs a flanged barrel. In the Lewis patent and in other prior art patents such as U.S. Pat. No. 4,058,050, there are no means provided for accurately centering the barrel in the shroud. It has now been discovered by way of extensive testing that there is an interaction between the barrel and shroud during firing. During firing there is relative motion between the barrel and shroud along the barrel-shroud axis. With the use of prior art arrangements such as those described in the two above-mentioned patents, a relative shift occurs in an axial sense between the shroud and barrel contact surfaces, thus providing unpredictable bullet dispersion from the firearm. With the prior art arrangements, although the clearance between the barrel and shroud is quite small, this axial displacement between the barrel and shroud can cause misalignment therebetween and thus effect the bullet dispersion.
After extensive testing, it has been found that the accuracy of firing and in particular of rapid firing is effected by this lack of concentricity between the barrel and shroud bore. There may also be caused a contact between the outer diameter of the barrel and the inner diameter of the shroud bore. It has been found that this contact, even though it may be localized, effects the accuracy of firing or in other words, the point of impact of the projectile.
Accordingly, one object of the present invention is to provide an improved barrel, shroud construction, wherein the barrel is maintained concentric relative to the shroud bore to improve the accuracy of firing and in particular, rapid firing of the firearm.
When a hand gun, especially one of heavy magnum caliber is fired, many events occur within the weapon. In addition, especially at rapid firing there is a tendency for the barrel to heat and thus expand. These factors make it difficult to maintain a precise accuracy of firing from bullet to bullet. For example, when a hand gun of heavy magnum caliber is fired, a bullet of say 150-250 grain weight is accelerated under peak pressures of 40,000-50,000 lbs. per sq. in. pressure out of the cylinder and into the barrel. This causes an engraving of the outside of the bullet with the rifling of the barrel forcing the bullet down and out of the barrel. During firing the hand gun experiences a tremendous shock which establishes vibrations and bending moments in the hand gun. It is during this actual firing cycle that we are maintaining the barrel and shroud components in a uniform position and in that way enhancing the accuracy of the weapon. If accurate concentricity is not maintained, then there may be locations along the barrel where there is contact at its outer diameter with the inner diameter of the shroud. These local points of contact between the barrel and shroud effect the point of impact of the projectile. Therefore, one purpose of the invention is to maintain this concentricity even during rapid firing.
With prior art arrangements not employing the principles of the present invention, the barrel may seat at its outer end in different relationship to the shroud after each firing. This, along with the quite close tolerance of the barrel to the shroud provides for inconsistencies in the placement of the barrel relative to the shroud from firing to firing. Thus, with the prior art arrangements, the barrel may at one time be perfectly concentric in the shroud and after firing may the next time be seated closer to one portion of the inner wall of the shroud than another portion. It is these inaccuracies that result in possible firing inaccuracies.
Another object in accordance with the invention, therefore, is to maintain this concentric relationship of the shroud to the barrel and further provide an increased tolerance between the barrel and shroud. In this way, with the centering arrangement of this invention and the increased tolerance there is far less likelihood of any contact points even on a local basis between the outer diameter of the barrel and the inner diameter of the shroud.